Due to the rising cost of liquid fuel (e.g., diesel fuel), engine manufacturers have developed gaseous-fuel and dual-fuel engines that utilize low-cost gaseous fuel (e.g., natural gas). In these types of engines, gaseous fuel is introduced into the engine cylinders for subsequent combustion and production of mechanical power. In some engines (e.g., some dual-fuel locomotive engines), gaseous fuel is injected into each cylinder through air intake ports during an air intake portion of each engine cycle. The gaseous fuel mixes with the intake air to create a mixture that is combustible when ignited, such as via compression or ignition of a small amount of diesel fuel. These engines often include turbochargers that increase the power density of the engine by compressing and increasing the amount of air transferred to the engine and thus the amount of fuel that can be combusted during each engine cycle. The compressed air may be transferred into an air box associated with a cylinder bank and supplied through the air intake ports in the sides of each cylinder.
An example of a dual-fuel engine is described in U.S. Pat. No. 4,527,516, which issued to Foster on Jul. 9, 1985 (“the '516 patent”). The '516 patent discloses an engine that includes a supercharger that introduces intake air into an air chamber that surrounds each bank of cylinders. The intake air may be transferred from the air chamber to the engine cylinders through air intake ports. The engine of the '516 patent also includes a gas inlet pipe that introduces gaseous fuel into an engine cylinder through one of the air intake ports. The gaseous fuel mixes with the intake air for subsequent combustion to power the engine.
The engine of the '516 patent may suffer from problems associated with the introduction of supercharged intake air into the air chamber. For example, depending on the arrangement of the supercharger, the intake air flowing through the air chamber of the '516 patent may force gaseous fuel injected by the gas inlet pipe to exit a cylinder through the air intake ports and enter the air chamber. The escaped gas may subsequently enter a different cylinder, causing a uneven distribution of gaseous fuel in the engine cylinders.
This issue may be especially problematic with engines that include a turbocharger (or supercharger) that introduces compressed air into only one end of a cylinder bank. Due to its proximity, the cylinder that is closest to the turbocharger may experience higher variations of air flow rate across its air intake ports than the rest of the cylinders (e.g., higher flow rates at intake ports facing the turbocharger). The higher variation of air flow rate may cause injected gaseous fuel to escape and enter an air box that surrounds the cylinders. Therefore, in these applications, the cylinder closest to the turbocharger may be especially susceptible to experiencing a reduction in gaseous fuel concentration as compared to the rest of the cylinders in the cylinder bank.
The present disclosure is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.